The Section focuses its research on the functions of the human prefrontal cortex and cognitive neuroplasticity. We continue to refine a model developed in the Section that specifies some of the characteristics of the prefrontal cortex's underlying cognitive architecture and representational knowledge. We have determined that ease of access to knowledge stored in the prefrontal cortex is determined by the category and familiarity of that knowledge. In addition, failure to selectively retrieve such knowledge leads to impaired plan development and/or execution. Activating knowledge stored in prefrontal cortex allows that knowledge to manage information that has to be kept temporarily active. Social and non-social knowledge may be distinctively stored in the prefrontal cortex. Access to such knowledge helps modulate more primitive behaviors such as aggression. In an effort to better understand some aspects of cognitive neuroplasticity, we have examined the learning rate of patients recovering from brain damage and with deficits on the task of interest and compared their performance to matched controls. There is some indication that patients can show new learning in deficit areas but it is not clear that if new learning is without a cost to preserved cognitive functions. The section also utilizes positron emission tomography (PET), functional magnetic resonance imaging (fMRI), Direct Current Polarization (DCp) and transcranial magnetic stimulation (rTMS) to map planning processes, representational knowledge, reasoning processes, social cognition, reward systems, number processing and calculation to brain. For example, we have determined with fMRI the importance of the anterior prefrontal cortex for multitasking, task-switching, and adaptive behavior. We have used rTMS to facilitate the speed of analogical reasoning in healthy normal control subjects possibly providing a framework to use rTMS to aid rehabilitation of brain-injured patients. The Section utilizes data from normal control studies, patient studies, functional neuroimaging, and rTMS to provide convergent evidence about the functions of the human prefrontal cortex and cognitive neuroplasticity.